(function() {
  interface Person {
    name: string,
    age: number,
    address: string
  }

  function greeter(person: Person): string {
    return "Hello, " + person;
  }
  
  let user = {
    name: '张三',
    age: 15,
    address: '成都'
  };
  
  document.body.innerHTML = greeter(user);

  let isDone: boolean = true

  isDone = false

  let array: number[] = [3, 1, 2]
  let arr: Array<string> = ['a', 'b', 'true']

  enum Direction { Up, Down, Left, Right }

  let direction = Direction.Up

  let x = 3

  // x = 'abc'
})()
